Agent Orange
and Prostate Cancer

Why are Vietnam veterans worried about prostate cancer?

Prostate cancer is one of the most common cancers among men. The rate varies
dramatically by age and race. The risk of getting prostate cancer increases
fivefold between the ages of 45-49 and 50-54 years, and nearly triples between
50-54 and 55-59. African-American men have the highest recorded incidence
of prostate cancer in the world. Their risk is approximately double that
of white men. The causes of prostate cancer are uncertain. Risk factors other
than race and age include a family history of the disease and a diet high
in fats. Prostate cancer is expected to account for about 29 percent of new
diagnoses and 13 percent of cancer death per year in the United States.

Some Vietnam veterans have already reached, while many are approaching,
the age when prostate cancer is typically detected. Since prostate cancer
is a slow-growing tumor, many men diagnosed with prostate cancer will actually
die from other unrelated causes. Nevertheless, prostate cancer is the second
leading cause of death in men. It is estimate that more than 200,000 cases
of prostate cancer (including about 10,000 veterans) will be diagnosed annually
with an approximately 40,000 death. A problem with prostate cancer is that
in about 40 percent of the cases the tumors have spread beyond the prostate
before it is diagnosed, making treatment more difficult.

How is prostate cancer detected?

There are currently three methods of screening: (1) digital rectal examination,
(2) transrectal ultrasound, and (3) prostate specific antigen (PSA, a blood
test to measure a protein found only in prostate tissue). Unfortunately,
there are significant problems with each of these screening techniques. For
each cancer detected, there are many false positives that may incorrectly
diagnose a patient as having prostate cancer.

What treatments are available?

Since prostate cancer is a relatively slow-growing tumor compared to other
cancers, the paradox in managing it is the need to intervene early to stop
the disease and also being cautious about using the major treatment, a surgery
known as radical prostatectomy. This is a serious procedure with significant
complications. From 25 to 75 percent of patients will be impotent and 2 to
6 percent severely incontinent after the surgery.

In addition to surgery, current treatments for prostate cancer include
radiation therapy, which also has some unpleasant side effects, and male
hormone (androgen) deprivation. Chemical or surgical deprivation or administration
of estrogen is effective in relieving pain, reducing urinary obstruction,
and improving general well-being. Endocrine therapy delays disease progression,
but has not been shown to prolong survival.

A relatively new approach to treatment is known as “expectant management,” which
means following the patient and giving hormonal or surgical treatment as
necessary. This approach is reasonable because the progression of the tumor
for each patient is uncertain, the treatment effectiveness is uncertain,
and many patients with prostate cancer eventually die of other causes.

What did the National Academy of Sciences (NAS) conclude about the relationship
between exposure to herbicides and the development of prostate cancer in
its 1993 report, entitled Veterans and Agent Orange - Health Effects of Herbicides
Used in Vietnam?

The NAS reviewers observed that most of the agricultural studies they examined
indicate “some elevated risk” of prostate cancer. Furthermore,
one large well-done study in farmers showed an increased risk, and subanalyses
in this study indicate that the increased risk specifically associated with
herbicide exposure. The three major production worker studies reviewed by
the NAS all show a small, but not statistically significant, elevation in
risk. The NAS report noted that most of the associations seen in the studies
reviewed are “relatively weak.” The NAS added that Vietnam veterans
have “not yet reached the age when this cancer tends to appear.” In
the report released in July 1993, the NAS concluded that there is “limited/suggestive
evidence” of an association between exposure to herbicides used in
Vietnam and prostate cancer.

What action did VA take in response to this NAS finding?

In its July 1993 report, the NAS placed three health outcomes in its second
highest category of association (limited/suggestive evidence of an association):
multiple myeloma, respiratory cancers, and prostate cancer. After careful
review, VA’s Secretary Brown concluded that the credible scientific
evidence for an association is equal to or outweighs the evidence against
an association between exposure to herbicides used in Vietnam and the development
of multiple myeloma and of respiratory cancers. On the other hand, the evidence
for an association between these herbicides and prostate cancers failed to
reach that standard.

In January 1994, VA published a notice in the Federal Register that Secretary
Brown has determined that a presumption of service connection based on exposure
to herbicides used in Vietnam is not warranted for a long list of conditions
identified in the NAS report. Prostate cancer was included in this list.
(See 59 Fed. Reg. 341, January 4, 1994).

VA asked the NAS, in its follow-up report, to further consider the relationship
between exposure to herbicides and the subsequent development of prostate
cancer.

What did the 1996 NAS update conclude about prostate cancer?

Citing additional studies, the NAS report concluded that there is “limited/suggestive
evidence” of an association between exposure to herbicides used in
Vietnam and prostate cancer.

What was VA’s response to the NAS 1996 finding regarding prostate
cancer?

Secretary Brown found that the credible evidence for an association equals
or outweighs the evidence against an association between exposures to herbicides
used in Vietnam and prostate cancer. He concluded that prostate cancer should
be added to the list of conditions recognized for presumption of service
connection for Vietnam veterans based on exposure to herbicides. President
Clinton announced this, along with other decisions, on May 28, 1996. The
proposed rule to implement this decision was published for public comment
in the Federal Register in August 1996. (See 61 Fed. Reg. 41368, August 8,
1996). The final rule was published in the Federal Register in November 1996.
(See 61 Fed. Reg. 57587, November 7, 1996).

What did the subsequent NAS updates conclude about prostate cancer?

The 1998 report concludes that there is limited/suggestive evidence of
an association between exposure to the herbicides used in Vietnam and prostate
cancer. The report includes the following statement:

Although the associations are not large, a number of studies provide evidence
that is suggestive of a slight increase in either morbidity or mortality
from prostate cancer. The evidence regarding association is drawn from occupational
studies in which subjects were exposed to a variety of herbicides and herbicide
components and is also based on data from studies of Vietnam veterans. An
important consideration is the fact that prostate cancer tends not to be
fatal; thus, mortality studies have lower statistical power to detect a comparable
effect than a similar-sized morbidity study would have.

In the 2000 update, the NAS concluded that there is limited/suggestive
evidence between exposure to herbicides and prostate cancer. Although the
associations are not large enough, there are a number of studies providing
evidence suggestive of a small increase in either morbidity or mortality
from prostate cancer.

The 2002 report also concludes there is limited/suggestive evidence of
prostate cancer being linked to exposure to herbicides. The associations
are not large but there are studies providing evidence that suggest a small
increase in either morbidity or mortality from prostate cancer.

Where can a veteran get additional information about prostate cancer?

Information regarding prostate cancer and related matters can be obtained
at VA medical center libraries, from the Environmental Health Clinicians
at every VA medical center, or from the Environmental Agents Service (131),
Department of Veterans Affairs, 810 Vermont Avenue, N.W., Washington, DC
20420.

The October 2001 and March 2002 issues of the VA’s Agent Orange Review
newsletter reprint in two parts an excellent brochure provided by the American
Urological Association (AUA). The Web address for the AUA is www.auanet.org.
The Agent Orange Review can be seen at the Web site listed below.

Where can a veteran get additional information regarding Agent Orange – related
issues?